I don't mean to be flipant but this needs to be said... Have you gone bonkers??
The US airline industry is probably in the worst state it's ever been and you want to give up the relative stability of a European Flag Carrier? Don't do it.
I've been here 7 years, it wasn't part of the masterplan but just the way things worked out. I'm apprecative of the opportunities the US has given me, had the chance to fly with some of the best out there but if I had it to do all over again I would've hightailed it back to Oz or the UK.
In my time I've been furloughed, just like thousands of others, and I'm still in the right seat of an RJ at 5000 hours working for $36 an hour.
Stay at BA and you might get to retirement without being furloughed, losing your job or going insane.